JP5107867B2 - Porous solid lubricant - Google Patents

Description

  The present invention relates to a porous solid lubricant capable of supplying lubricating oil to a sliding part and a rotating part of a mechanical device.

  Generally, a lubricant is used in a sliding part and a rotating part of most machines represented by automobiles and industrial machines. Lubricants can be broadly divided into liquid lubricants and solid lubricants. Grease with increased lubricating oil and shape retention, and solids that retain liquid lubricant and prevent its splashing and dripping. Lubricants are also known.

  For example, a solid lubricant in which ultra-high molecular weight polyolefin or urethane resin and its curing agent are mixed in lubricating oil or grease, and a liquid lubricant component is held between the resin molecules to gradually exude physical properties. Known (Patent Documents 1, 2, and 3).

  Also known is a self-lubricating polyurethane elastomer obtained by reacting a polyol, which is a polyurethane raw material, with a diisocyanate in a lubricating component in the presence of a lubricant (Patent Document 4).

  When such solid lubricant is sealed in a bearing and solidified, it gradually exudes lubricating oil. If this is used, maintenance for replenishing the lubricating oil becomes unnecessary, and there is a lot of moisture. In many cases, it is useful for extending the life of the bearing even in environments where it is used or where there is a strong inertia.

  However, if such a solid lubricant is used at a site where external stress such as compression or bending is repeatedly applied at a high frequency, such as a drive part of a constant velocity joint, it is very difficult to deform following the compression and bending. A large force is required, or a very large stress is applied to the solid lubricant, and a mechanical strength is also required in a portion that holds the solid lubricant.

  However, since the strength and filling rate of the solid lubricant are usually compensatory, it is difficult to keep the lubricant at a high filling rate, which may hinder a longer life.

  Therefore, there is a demand for a solid lubricant that can be easily used even at sites where external stress such as compression and bending repeatedly occurs at a high frequency.

  It is known that oil-impregnated solid lubricant, which is made by impregnating lubricating oil into a flexible resin that has foamed and formed continuous air holes, and that holds the lubricating oil in the pores, is also used by filling the bearings and constant velocity joints. (Patent Document 5).

JP-A-6-41569 JP-A-6-172770 JP 2000-319681 A Japanese Patent Laid-Open No. 11-286601 JP-A-9-42297

  However, the above-described solid lubricants according to the prior art have flexible deformability according to external force and can follow compression and bending deformation, but have a low lubricating oil retention force and are used under high speed conditions such as bearings. In some cases, the lubricant can quickly escape and be depleted.

  Such oil-impregnated solid lubricants can be used in short-time lubrication and sealed spaces, but when used in parts that require long-term lubrication or in open spaces, the lubrication oil will be insufficiently supplied, or the oil will be retained. If the force is weak, excess lubricating oil will be repeatedly released and absorbed from the pores and will endure and flow in the space.

  When the lubricant exuded excessively from such a solid lubricant comes into contact with an exterior such as rubber, the lubricant and its additives may be chemically corroded or deteriorated.

  In addition, in the process of manufacturing such a solid lubricant, many manufacturing processes are required for reliably impregnating the lubricant and grease, and it is difficult to meet the demand for cost reduction.

  Accordingly, an object of the present invention is to solve the above-described problems, improve the holding power of the solid lubricant that holds the lubricating oil, and keep the amount of lubricating oil oozed out by deformation due to external force to the minimum necessary. It is to make it a solid lubricant.

  Furthermore, it is to provide a solid lubricant that can solve the above-mentioned problems and can simplify the manufacturing process and meet the demand for cost reduction.

  In order to solve the above problems, in the present invention, a lubricating component including a lubricating oil and a resin component are essential components, the resin component is a foamed and porous solid, and the lubricating component is disposed inside the resin. This is a porous solid lubricant that is occluded.

  In the present invention, “occlusion” means that a liquid (liquid lubricant or the like) is contained in a solid resin without becoming a compound, as in the meaning of the term “occlusion”.

  In this invention, since the lubricating component is occluded in the resin in a foamed state of the resin component, the flexibility of the resin causes the lubricating component to exude by deformation due to external force such as compression, expansion, bending, and twisting. Slow release from between molecules to the outside. At this time, the amount of lubricating oil that oozes out can be minimized by changing the degree of elastic deformation according to the magnitude of the external force by selecting the resin component.

The foamed resin component, it is foamed resin component to be a continuous gas Awanai lubricating component ratio of 50% or more, impart an effect of sufficiently appropriate amount just bleeding out by deforming the lubricating component in the pores Therefore, it is preferable.

  In addition, the resin component having rubber-like elasticity made of resin or rubber has a large surface area due to foaming, and it is possible to temporarily hold the excess lubricating oil that has oozed out in the pores. Even if there is, the amount of lubricating oil that oozes out is relatively stable, and the lubricating component is occluded in the resin, and by impregnating the pores, the amount of lubricating oil retained is larger than in the non-foamed state.

  In addition, the porous solid lubricant according to the present invention requires very little energy when bent compared to a non-foamed material, and can be flexibly deformed while holding the lubricating oil at a high density. Moreover, since it has many foamed parts, ie, a porous part, it is advantageous also at the point of weight reduction.

  In order to obtain a porous solid lubricant exhibiting such an action, it is preferable to set the foaming ratio of the resin component to 1.1 to 100 times, and that the resin component is a polyurethane resin, It is preferable to ensure elasticity and occlusion corresponding to the thickness.

  This invention comprises a resin component and a lubrication component, and the resin component has occluded the lubrication component in the resin in a foamed state, so that the retention force of the solid lubricant that holds the lubricating oil is improved and by external force There is an advantage that the amount of lubricating oil that oozes out by deformation can be minimized.

  In addition, the manufacturing process can be made relatively simple, and there is an advantage that the demand for cost reduction can be met.

  As the resin component constituting the porous solid lubricant of the present invention, either or both of an elastomer and a plastomer can be adopted as an alloy or a copolymer component among a resin (plastic) or rubber.

  In the case of rubber, various rubbers such as natural rubber, isoprene rubber, butadiene rubber, styrene butadiene rubber, chloroprene rubber, butyl rubber, nitrile rubber, ethylene propylene rubber, silicone rubber, urethane elastomer, and fluoro rubber chlorosulfone rubber can be employed.

  For plastics, polyethylene, polypropylene, polystyrene, polyvinyl chloride, polyacetal, polyamide 4, 6 (PA4, 6), polyamide 6, 6 (PA6, 6), polyamide 6T (PA6T), polyamide 9T (PA9T) General-purpose plastics and engineering plastics.

  Moreover, it is not restricted to said plastics etc., Polyurethane foams, such as a flexible urethane foam, a rigid urethane foam, a semi-rigid urethane foam, a polyurethane elastomer, etc. can also be used.

  Various adhesives such as urethane adhesives, cyanoacrylate adhesives, epoxy resin adhesives, polyvinyl acetate adhesives, polyimide adhesives, and the like can also be used after being foamed and cured.

  If necessary, various additives such as pigments, antioxidants, metal deactivators, antistatic agents, flame retardants, antifungal agents, and fillers can be added to the solid component.

  The solid lubricant of the present invention comprises a lubricating component and a resin component as essential components, and can supply lubricating oil to the outside by external stress such as compression, bending, centrifugal force, and expansion of bubbles accompanying a temperature rise. is there.

  The bubbles generated when the pores are formed by foaming are preferably continuous pores, and the lubricating component is directly supplied from the surface of the resin to the outside through the continuous pores due to external stress. In the case of the independent holes, the entire amount of the lubricating oil in the solid component may be temporarily taken into the bubbles and not sufficiently supplied to the outside when necessary.

Then, the resin component was foamed in this invention is preferably a foamed resin component to be a continuous gas Awanai lubricating component ratio of 50% or more. The continuous gas Awanai lubricating component ratio is less than a predetermined value, many ratio lubricating oil of the resin component (solid component) is incorporated into temporarily closed cell, preferably it is often not supplied to the outside even when necessary Absent.

The ratio of the lubrication component in open cells adjusted in the present invention is a technical variable that can be calculated as follows.
(1) First, a foamed and cured porous solid lubricant cut to a size suitable for weight measurement is designated as A, and the weight is measured. The resin component weight is calculated.
(2) Next, the above measured A was subjected to Soxhlet cleaning for 3 hours using petroleum benzine as a solvent, and then placed in a thermostatic bath at 80 ° C. for 2 hours to completely dry the organic solvent. Is defined as B, and the weight B (resin component + lubricant incorporated into closed cells) is measured.
(3) From the values of the obtained lubricating component weight of A, the resin component weight of A, and the weight of B , the lubrication component ratio in the open cell is calculated by the following formula.
Percentage of lubrication component in open cell (%) = {1− (weight of resin component of B−A) / weight of lubrication component of A} × 100
According to the above formula, since the lubricating component taken into the discontinuous closed cells is not released to the outside by Soxhlet cleaning for 3 hours , the lubricating component ratio in the open cells can be calculated by the above operation.

  In order to occlude the lubricating component inside the resin, it is desirable to employ a reactive impregnation method in which a foaming reaction and a curing reaction are simultaneously performed in the presence of a lubricant. In this way, it is possible to highly fill the inside of the resin with the lubricant, and thereafter, the post-impregnation step of impregnating and replenishing the lubricant can be omitted.

  On the other hand, a foam solid body is molded in advance, and only a post-impregnation method in which the solid is impregnated with a lubricant does not allow a sufficient amount of liquid lubricant to penetrate into the resin. However, if the lubricating oil is released in a short time and used for a long time, the lubricating oil may be insufficiently supplied. For this reason, the post-impregnation step is preferably employed as an auxiliary means for the reactive impregnation method.

  The reactive impregnation method is preferably performed by using a surfactant such as a commercially available silicone-based foam stabilizer and dispersing each raw material molecule uniformly. Further, it is possible to control the surface tension by controlling the type and amount of the foam stabilizer, and to control the properties of the resulting bubbles (continuous type / independent type) and the size of the pores. Examples of the surfactant include an anionic surfactant, a nonionic surfactant, a cationic surfactant, an amphoteric surfactant, a silicone surfactant, and a fluorine surfactant.

  The ratio of the lubricating oil (100% by weight) of the lubricating oil is preferably 1% by weight to 95% by weight, more preferably 5 to 80 parts by weight. When the ratio of the lubricating oil is less than 1% by weight, it is difficult to sufficiently supply the lubricating oil to a necessary portion. In addition, when a large amount exceeds 95% by weight, the grease does not harden even at low temperatures and remains in a liquid state, and may not perform a function specific to the solid lubricant.

  The lubricating oil used in the present invention can be used without any choice as long as it does not dissolve the foamed solid component forming the foam. For example, lubricating oil, grease, wax, etc. may be used alone or in combination. It may be used.

  As the lubricating oil used in the present invention, paraffinic and naphthenic mineral oils, ester synthetic oils, ether synthetic oils, hydrocarbon synthetic oils, GTL base oils, fluorine oils, silicone oils and the like are commonly used. Lubricating oils or mixed oils thereof.

  If the resin material and the lubricating oil do not dissolve or disperse due to chemical compatibility such as polarity, it is easier to physically mix and prevent segregation of the lubricant by using a lubricating oil with close viscosity. It becomes.

  Examples of the thickener for the grease used in the present invention include soaps such as lithium soap, lithium complex soap, calcium soap, calcium complex soap, aluminum soap, and aluminum complex soap, and urea-based compounds such as diurea compounds and polyurea compounds. However, it is not particularly limited.

  Examples of the urea thickener include, but are not particularly limited to, a diurea compound and a polyurea compound.

  The diurea compound is obtained, for example, by reaction of diisocyanate and monoamine. Diisocyanates include phenylene diisocyanate, diphenyl diisocyanate, phenyl diisocyanate, diphenylmethane diisocyanate, octadecane diisocyanate, decane diisocyanate, hexane diisocyanate, and monoamines include octylamine, dodecylamine, hexadecylamine, octadecylamine, oleylamine, aniline, p-Toluidine, cyclohexylamine and the like can be mentioned.

The polyurea compound can be obtained, for example, by reacting diisocyanate with a monoamine or diamine. Examples of the diisocyanate and monoamine include those similar to those used for the production of the diurea compound. Examples of the diamine include ethylenediamine, propanediamine, butanediamine, hexanediamine, octanediamine, phenylenediamine, tolylenediamine, and xylenediamine. Is mentioned.
As the base oil of the grease, the same lubricant oil as described above can be used.

  The wax used in the present invention may be any hydrocarbon synthetic wax, polyethylene wax, fatty acid ester wax, fatty acid amide wax, ketone / amines, hydrogenated oil, and the like. As the oil component used for these waxes, the same oil components as those described above can be used.

  Lubricating components as described above include solid lubricants such as molybdenum disulfide and graphite, friction modifiers such as organic molybdenum, oily agents such as amines, fatty acids, and fats, and antioxidants such as amines and phenols. Agents, rust inhibitors such as petroleum sulfonate, dinonyl naphthalene sulfonate, sorbitan ester, extreme pressure agents such as sulfur and sulfur-phosphorus, organic zinc, antiwear such as phosphorus, benzotriazole, sodium nitrite, etc. Various additives such as viscosity index improvers such as metal deactivators, polymethacrylates and polystyrenes may be included.

  As a means for foaming the solid component, a well-known foaming means may be employed. For example, a physical method for heating and vaporizing an organic solvent having a relatively low boiling point such as water, acetone, hexane, etc. A mechanical foaming method that blows active gas from the outside, such as azobisisobutyronitrile (AIBN) or azodicarbonimide (ADCA), which uses a decomposable foaming agent that decomposes by temperature or light and generates nitrogen gas, etc. The method of doing etc. is mentioned. Moreover, when it has a highly reactive isocyanate group as a raw material, you may use the chemical foaming by the carbon dioxide produced by the chemical reaction with it and a water molecule.

  In order to use foaming accompanied by such a reaction, it is desirable to use a catalyst as necessary. For example, a tertiary amine catalyst or an organometallic catalyst is used.

  Examples of the tertiary amine catalyst include monoamines, diamines, triamines, cyclic amines, alcohol amines, ether amines, imidazole derivatives, and acid block amine catalysts.

  As organometallic catalysts, stanaoctaate, dibutyltin diacetate, dibutyltin dilaurate, dibutyltin marker butylide, dibutyltin thiocarboxylate, dibutyltin maleate, dioctyltin dimarkaptide, dioctyltin thiocarboxylate, phenylmercury propion Examples thereof include acid salts and lead octenoate. Moreover, you may mix and use these multiple types for the purpose of adjusting the balance of reaction.

  The expansion ratio of the foamed lubricant is desirably 1.1 to 100 times. This is because when the foaming ratio is less than 1.1 times, the bubble volume is small, and deformation is not allowed when external stress is applied, or the solid matter is too hard to deform. In addition, when the expansion ratio exceeds 100 times, it is difficult to obtain a strength that can withstand external stress, and damage or destruction may occur during use.

  The solid lubricant that has been solidified may be cast into a mold and molded, or after solidification at normal pressure, it may be post-processed into a desired shape by cutting or grinding.

  The raw materials used in the examples and comparative examples are listed below collectively, and the composition and measurement results of the solid lubricant are shown in Table 1.

(A) Urethane prepolymer (Daicel Chemical Industries, Plaxel EP-1130)
(B) Amine-based curing agent (Ihara Chemical Co., Ltd .: Iharacamine MT)
(C) Water (ion exchange water)
(D) Silicone-based foam stabilizer (manufactured by Toray Dow Co., Ltd .: SRX298)
(E) Urea grease (Pyronoc Universal N6C, Nippon Oil Corporation)
(F) Isocyanate (manufactured by Nippon Polyurethane Co., Ltd .: Coronate T80)
(G) Polyether polyol (Asahi Glass Co., Ltd .: Preminol SX4004)
(H) Amine-based catalyst (Tosoh Corporation: TOYOCAT DB2)
(I) Lubricating oil (manufactured by Nippon Oil Corporation: Turbine 100)

[Examples 1 and 2]
Silicone foam stabilizers and urea grease were added to the urethane prepolymer with the component amounts (composition) shown in Table 1, and the mixture was well stirred at 120 ° C. An amine-based curing agent was added and stirred, and then water as a foaming agent was added and allowed to cure in a constant temperature bath set at 120 ° C. for 1 hour to obtain a foamed solid lubricant.

[Example 3]
In the component amounts (composition) shown in Table 1, silicone foam stabilizer, mineral oil, amine catalyst, and water as a foaming agent were added to polyether polyol, and heated at 90 ° C. and well stirred. After adding isocyanate to this and stirring well and confirming a foaming reaction, it was left to stand for 15 minutes in a thermostat set at 90 ° C. to obtain a foamed solid lubricant.

[Comparative Example 1]
A non-foamed lubricant was obtained by the same production method as in Example 1 with the component amounts (composition) shown in Table 1.

[Comparative Example 2]
Of the components (compositions) shown in Table 1, a foam was synthesized in the same manner as in Example 2 except for mineral oil. The oil was impregnated later to obtain a post-impregnation type foaming lubricant.

[Reference example]
Of the components (compositions) shown in Table 1, a foam was synthesized by the same method as in Example 3 except for the silicone foam stabilizer, and a solid lubricant having an in-open-cell lubricating component ratio of less than 50% was obtained.

The obtained solid lubricant was measured for each item of expansion ratio and rebound resilience, centrifugal oil separation, and the ratio of lubricating components in open cells , and comprehensively determined whether or not it could be used. In addition, the measuring method of impact resilience was based on JISK6400-3.

Centrifugal oil separation indicates the oil reduction rate with respect to the oil filling amount when rotated for 1 hour under the conditions of a rotor radius of 75 mm and a rotational speed of 1500 rpm / min. In addition, the lubrication component ratio in the open cell was calculated based on the measurement method using the above formula.

  As is apparent from the results shown in Table 1, the foamed Examples 1 and 2 have a larger elastic deformation amount than the non-foamed Comparative Example 1 even under the same kinetic energy (under inertial force) (repulsion). It can be seen that the elastic modulus is small) and the shape follows a strong shape against compression deformation. Thus, it can be seen that the foamed solid lubricant of the example can withstand use even in a driving space to which external stress such as compression, which has been impossible in the past, is applied.

  In addition, the solid lubricant of Comparative Example 2 in which the mineral oil was retained only in the post-impregnation step even with the foamed resin of the same composition was compared with Example 3 in which the mineral oil was occluded in the resin simultaneously with foaming under the same centrifugal force. There was a lot of oil separation. As a result, it was found that the lubricant was sufficiently occluded in the resin solids by impregnation with the reactive lubricant, and a solid lubricant having sustained release could be produced.

  In addition, from these examples and comparative examples, the lubricating oil is occluded in the resin by the reactive impregnation simultaneously with foaming, and the lubricating oil is retained in the bubbles simply by impregnating the foamed resin molding into the lubricating oil. It can be seen that the oil retention by occlusion is higher than that of the case.

Furthermore, in the reference example in which the ratio of the lubrication component in the open cell is less than 50%, it is inferior in the point that the amount of oil separation under the centrifugal force is smaller than in Example 3, but the rebound elastic modulus and the like are comprehensively taken into consideration. In this case, it was able to withstand use within the scope of the present invention.

Claims (5)

A resin component comprising a lubricating component containing lubricating oil and a rubbery resin or rubber is an essential component, and the resin component has a lubricating component weight in open cells of 50 to 80% with respect to the total weight of the lubricating component. foaming to be porous are solids having closed cells and open cells as by reactive impregnation method in the presence of a lubricant causing foaming reaction and curing reaction at the same time, the lubricating component, the resin internal A porous solid lubricant that is dispersed in the open cell and occluded in open cells and closed cells, and has a leaching property of a lubricating component by an external force . The porous solid lubricant according to claim 1, wherein the foaming ratio of the resin component is 1.1 to 100 times. The porous solid lubricant according to claim 1 or 2 , wherein the resin component is a polyurethane resin. Either the resin component is chemically foamed by carbon dioxide generated by a chemical reaction between isocyanate groups in the raw material and water molecules, physically foamed by vaporization of water or an organic solvent, or mechanically foamed by blowing air or an inert gas. The porous solid lubricant according to any one of claims 1 to 3, wherein the porous solid lubricant is foamed and made solid. The porous component according to any one of claims 1 to 4, wherein the lubricating component is a grease thickened with a urea-based thickener, and the resin component is a solid material formed by foaming with water as a foaming agent. Solid lubricant.